Physicist receives NSF CAREER award for work with quantum nanomachines

Grant will enable Matthew LaHaye to expand research

Mar 9, 2011

Article by: Judy Holmes

Matthew LaHaye, assistant professor of physics in Syracuse University’s College of Arts and Sciences, received a five-year, $600,000 National Science Foundation Early Career Development (CAREER) Award to further his research in the emerging field of quantum nanoelectromechanical systems (NEMS). The prestigious award recognizes outstanding scientists and engineers who, early in their careers, show exceptional potential for leadership.

NEMS are tiny widgets that can only be seen by very high-powered microscopes. Scientists believe that under the right conditions, NEMS should follow the laws of quantum mechanics but, until recently, lacked the technology to study their properties at the quantum level. As a post-doctoral researcher at the California Institute of Technology (Caltech), LaHaye developed a new technique to measure quantum behavior in tiny, nanometer-sized mechanical devices he designed. It was groundbreaking work that was published in 2009 in Nature.

“Quantum mechanics was developed to describe how matter behaves at unimaginably small scales—in the realm of atoms and the particles that make up atoms,” LaHaye says. “However, there is nothing in the theory that says these same laws cannot apply to larger objects made up of billions of atoms.”

LaHaye’s CAREER award will enable him to probe this area of fundamental physics, which seeks to learn how and why the laws of quantum mechanics give way to classical physics. Additionally, the award will enable him to further study and develop NEMS, which are being actively explored for a variety of applications. “NEMS are likely to play an important role in the next generation of biological sensors, probes, imaging systems, and other tools to enhance medical and scientific research,” LaHaye says.

Classical laws of physics describe the behavior of pretty much everything in our world that is larger than an atom. Examples include Newton’s laws of motion and Einstein’s theory of general relativity. Quantum mechanics describes some very strange things that seem to happen only at the smallest scales of nature and at very cold temperatures, including the observation that qubits—basic units of quantum information —can seemingly exist in two states at once.

“We can study NEMS to determine whether there are limits on quantum mechanics,” LaHaye says. “Likewise, our research might lead to new insights about quantum mechanics as we move to large-scale structures.”

LaHaye’s NEMS are built with a tiny beam suspended over a small space. The beam is typically several microns long and hundreds of nanometers wide and made of conventional materials, such as aluminum and silicon nitride. In the work LaHaye will be doing with his CAREER grant, the beams will be coupled with a superconducting qubit and the entire unit cooled to almost absolute zero. Strangely enough, even at such low temperatures the tiny beam vibrates when a small voltage is applied.

The work LaHaye and his colleagues did at Caltech demonstrated, for the first time, that scientists could successfully couple a qubit, consisting of paired electrons, to a mechanical device, consisting of billions of atoms, and make the two parts work together. Furthermore, they demonstrated how to measure the quantum behavior in the qubit using the NEMS. The next step is to use the qubit to demonstrate the quantum behavior of the NEMS, which is one of the focal points of LaHaye’s current research.

“The qubit-coupled NEMS system has great potential to serve as a toolbox for studying and even controlling quantum behavior in an entirely new experimental realm,” LaHaye says. “Only a handful of research groups in the world are pursuing this approach. Once we get the system up and running at SU, we’ll be in a position to perform some really unique and important experiments to probe new limits of the quantum world.”

LaHaye holds a Ph.D. in experimental condensed matter physics from the University of Maryland at College Park and a bachelor’s degree in physics and philosophy from the University at Albany, State University of New York. Prior to coming to SU in 2009, LaHaye was a Center for Physics of Information post-doctoral scholar at Caltech and a member of Michael Roukes’ research group. Roukes is the co-director of Caltech’s Kavli Nanoscience Institute.